We can not cure HIV, but antiretroviral therapy has extended life for HIV
positive clients. The goal of antiviral therapy is to lower the viral count
in the bloodstream. There are three major classes of drugs. Despite this
progress, these drugs typically lose their effectiveness after a period
of treatment because the virus mutates and becomes resistant, much like
bacterial resistance to antibiotics. Cross-resistance, or the virus' ability
to mutate to be resistant to multiple drugs of the same class, is also a
Nucleoside Reverse Transcriptase Inhibitors
- The drugs work by blocking the reverse transcription mechanism in HIV.
Reverse transcription is a necessary step to incorporate HIV into human
cells, therefore preventing the virus from being taken up by the cell.
This inhibits the virus' ability to reproduce. It is the most studied drug
class to date. Drugs of this class include AZT, videx, HIVID, and Epivir,
Non-Nucleoside Reverse Transcriptase Inhibitors
- This drug class also blocks reverse transcription in HIV, but differently than NRTI's. These drugs are available through prescription.
Drugs in this class include Viramune, Rescriptor, and Sustiva.
- This is the newest class of antiviral drugs. Tlhey block the action of protease, a protein the virus must have in order to reproduce and
infect new cells. This allows these drugs to block, or at least minimize, mutations. This class has drugs like Invirase, Norvir, and Viracepta.
Effects on Antiviral Therapy on Viral Burder
- Monotherapy, the use of one drug to treat infection, typically results in
a relatively small drop in viral burden, followed by a spike in viral levels,
and sometimes drug resistant strains. Combination therapy, typically three
or more drugs used in tandem has been shown to significantly decrease viral
load, even over a sustained period of time. "several such studies showed
that triple-drug combination therapy decreased the amount of viral RNA in
blood to below limits of detection" (JAMA) Antiviral therapy has shown
to decrease viral load in both semen and vaginal secretions.
This information must all be taken with a grain of salt. It is
possible that semen and vaginal secretions may be special circumstance which
responds differently to treatment. Studies are also contradictory, as viral
load may sometimes be detected in semen, even when it can't be detected
in the blood and vice versa.
The University of Arizona
Biology 181 Honors
Last updated: December 5, 2002
All contents copyright (c) 2002. All rights reserved.